X e eichaed geatzel



''UNITED STATES PATENT OFFI E.

J RICHARD GRATZEL, OF BREMEN, GERMANY, ASSIGNOR TO THE ALUMINIUM U ND MAGNESIUM FABRIK PATENT GRATZEL, OF SAME PLACE.

PRODUCTION OF ALUMIN IUM AND ALUMINIUM BRONZE.

SPECIFICATION forming part of Letters Patent No. 362,441, dated May 3, 1887.

Application filed December I, 1885.

T all whom it may concern:

Be it known that I, RICHARD Gnli'rznr, a

subjectof the King of Prussia, and residing at Bremen, German Empire, have invented new and useful Improvementsin the Production of Aluminium and Aluminium Bronze, of which the following is a specification.

My invention relates to the production of aluminium from the compound fluoride of IO aluminium and of an alkali metal; and it consis'ts in decomposing the aluminium fluoride of the said compound when being in melted con dition by means of magnesium, which may be employed in prepared state as metal or formed r5 in the bath of the melted fluoride by the electric decomposition of magnesium chloride. If. the electric current is called intoaid, the said magnesiiim chloride may be replaced by chlo-' ride of calcium, barium, or strontium. The invention also comprises the production of aluminium bronze by the introduction of copper into the melted bath from which the aluminium is obtained. If the compound fluoride ofaluminium and of an alkali metal, (especially of potassium or sodium) is melted and exposed to the action of magnesium, fluoride of magnesium is formed and'aluminium separates out in metallic state. The simplest mode of proceeding is to add magnesium in 0 solid or fused condition to the melted fluoric compound. At the beginning of the operation it is advantageous in such case to promote the mixture of the magnesium with the melted salt by stirring; but the magnesium may also first 3 5 be evaporated in a closed vessel, the vapor produced being conducted through a tube into the melted fluoric salt.

The third manner of carrying out the invention consists in producing the magnesium dur- 40 ing the process by electrolysis of chloride of magnesium. As is well known, this salt may be decomposed in fused state by the electric current, chlorine being evolved at the positive .pole, while the metal is deposited at the nega- 5 tive pole. Now, if the compound fluoride of aluminium and of an alkali metal is melted together with. chloride of magnesium, (preferably in the proportion of three equivalents of the chloride to one equivalent of fluoride of aluminium contained in the fluoric salt,) and Serial No. 184,986.

advantages that it maybe carried out with a (No specimens.)

5S nnnium fluoride, and metallic aluminium separates out.

As fluoric compounds of aluminium may be used native c'ryolite, (Al. ,F,,+6NaF,) or an artificial compound fluorideot' aluminium and 6 of an alkali metal. Moreover, it is to be ob served that, instead of simple chloride of magnesiu m, the compound chloride of magnesium and potassium or sodium-for instance, carnallite-or amixture of magnesicand potassic 6 or sodic chlorides, may beemployed with advantage, inasmuch asthe fused mass will thereby. become more fluid.

In comparison with the direct production of aluminium from the melted aluminium fluoride by electrolysis, to which relate my German Patent No. 26,962, and theBritish Patent No. 5,509, A. D, 1882, or from the double fluoride of aluminium and of an alkali metal, the process described in the foregoing presents the 7 n electric current of lower tension, and that the crucibles employed in the operation are not or but very little corroded (especially in the presence of chloride of potassium or sodium) by the fluoride of magnesium, or of magnesium and an alkali metal formed in the process, whereas the fluorine or comparatively pure fluoride of potassium or sodium produced by the former method acts in a high degree destructively on the crucibles. The latter advantage is also of importaneein respect to the employment of metallic magnesium, as compared with the decomposition of fluoride of aluminium by means of sodium. In like man- 0 ner, as by magnesium, the decomposition of fluoride of aluminium may be brought about by means of calcium, barium, and strontium; but on account of the great difficulties which the production of these metals present,- their 5 employment in regulineistate would, for the present at least, not be adapted to make the process remuncrative, The chlorides of calcium,'barium, and strontium may, however, be used, instead of chloride of magnesium, for

decomposing the .fluoridc of aluminium with the assistance of electricity. If, in addition to magnesium, copper is introduced into the melted compound fluoride, the same combines with the aluminium as it separates out and forms therewith aluminium bronze, In the electrolytic process a negative electrode consisting of copper may be used for this purpose.

I am aware that it has been proposed to obtain aluminium by subjecting anhydrous chloride or aluminium, the double chloride of aluminium and ammonium, the double chloride of aluminium and sodium, the double fluoride of aluminium and sodium to the action of heat and electrolytic action simultaneously. I am also aware of aprocess of reducing metals by electrolysis, in which a mixture of compoundsds used to increase the conductivity of the electrolyte or to lower the point of fusion-c. 9., the addition of calcium chloride to potassium. chloride or sodium chloride. I am further aware that it is not new to manufacture two metals-for instance, sodium and al uminiu m-si mul taneousl y from a double salt; and, still further, I am aware that it has been proposed, in the production of aluminiu m from the double chloride of aluminium and sodium by electrolysis, to add chloride of sodium, in order to allow the process to be carried out at a higher temperature; but such processes as above named are not the equivalent of my invention, and are very dissimilar thereto, for the reason that in said processes the very essential ingredient, chloride of magnesium, as

an accessory in the manufacture of aluminium from the double fluoride of aluminium and sodium, is not employed; and therefore I do not wish to claim, broadly, any features of the said processes as my invention; but

\Vhat I claim, and desire to secure by Let ters Patent, is-

l. The process of producing aluminium from the compound fluorideof aluminium and of an alkali metal by melting the said compound fluoride together with chloride of magnesium, or one of its aforesaid equivalents, (chloride of calcium, of barium, and of strontium,') and by causing an electric current to act on the molten mass, substantially as and for the purpose described.

2. The process of producing aluminium bronze from the compound fluoride of aluminium and of an alkali metal and from cop per by melting the said fluoride together with chloride of magnesium, or one of its aforesaid equivalents, (chloride of calcium, of barium, and of strontinm,) by introducing copper into the molten mass and by causing an electric current to act on the said mass, substantially as and for the purpose specified.

In testimony whereot'I have hereunto set my hand in the presence of two subscribing witnesses.

mormnn euli'rznt.

Witnesses:

Guns. A. ALBERTI, PAUL ROSTOCK. 

